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71.
The stable magnetization configurations of a ferromagnet on a quasiperiodic tiling have been derived theoretically. The magnetization configuration is investigated as a function of the ratio of the exchange to the dipolar energy. The exchange coupling is assumed to decrease exponentially with the distance between magnetic moments. It is demonstrated that for a weak exchange interaction the new structure, the quasiferromagnetic decagonal configuration, corresponds to the minimum of the free energy. The decagonal state represents a new class of frustrated systems where the degenerated ground state is aperiodic and consists of two parts: ordered decagon rings and disordered spin-glass-like phase inside the decagons. 相似文献
72.
The theory of spin-polarized low-energy electron diffraction (SPLEED) is outlined with an emphasis on symmetry-induced properties and models for the effective single-sphere potential. Details are given of the experimental set-up involving a new type of spin polarization detector based on SPLEED. Numerical calculations for the W(001)(1× 1) surface proceeded in close coordination with measurements of spin polarization (normal to the scattering plane) and intensity. A variety of calculated spin polarization and intensity profiles exhibits features, which are very sensitive to changes in the top interlayer spacing, as well as features sensitive to various ingredients of the potential model. The overall agreement between theory and experiment is very good not only for intensities, but also for spin polarization. It implies a contraction of the topmost interlayer spacing of W(001) with respect to the bulk spacing by 7% ± 1.5%, and supports the use of an energy-dependent exchange part and a nonuniform absorption part in the effective ion-core potential. 相似文献
73.
R. Kirschner 《Nuclear Physics B》1975,101(2):507-524
Energy-momentum conservation in the cluster production process is introduced in the independent cluster emission model using the generating functional formalism. In a simple version of the model clusters are produced which decay into a fixed number of pions. The ?? model and a model with isospin conservation in the cluster decay are used to calculate the charge distribution among the secondaries of cluster decay. Multiplicity characteristics like average multiplicity, second moments and associated average neutral multiplicities and second moments are calculated. The results are compared with experimental data. 相似文献
74.
Meyerheim HL Sander D Popescu R Kirschner J Robach O Ferrer S 《Physical review letters》2004,93(15):156105
The correlation between an ad-layer-induced spin reorientation transition (SRT) and the ad-layer-induced structural relaxation is investigated by combined in situ surface x-ray diffraction and magneto-optical Kerr-effect experiments on Ni/Fe/Ni(111) layers on W(110). The Fe-induced SRT from in-plane to out-of-plane, and the SRT back to in-plane upon subsequent coverage by Ni, are each accompanied by a small lattice relaxation of at most 0.002 A. Such a small strain variation excludes a magnetoelasticity driven SRT, and we suggest the interface anisotropy as a possible driving force. 相似文献
75.
Thamankar R Meyerheim HL Ernst A Ostanin S Maznichenko IV Soyka E Mertig I Kirschner J 《Physical review letters》2011,106(10):106101
Using scanning tunneling microscopy experiments in combination with first-principles calculations we have studied the geometric structure of the compressed c(7sqrt(2) × sqrt(2)) antiphase domain structure of CO on Cu(001). We find direct evidence for structural relaxations involving an inhomogeneous CO environment characterized by molecular tilting, bending, and nonterminal sites. Our analysis solves the long-standing problem of the adsorption structure of the compressed phase and is important for understanding the physical properties of this fundamental adsorption system. 相似文献
76.
R. Zimny H. Hagedorn H. Winter J. Kirschner 《Applied Physics A: Materials Science & Processing》1988,47(1):77-81
We observe the emission of circularly polarized light after grazing scattering of fast ions at a magnetized Fe(110) surface. Changing the state of magnetization of the target affects the polarization of the emitted light due to capture of spin polarized electrons. Some aspects of atom-surface interaction and investigations of surface magnetism are discussed. 相似文献
77.
M. Fippel R. Kirschner L. Szymanowski 《Zeitschrift fur Physik C Particles and Fields》1993,57(2):305-308
We investigate the asymptotics of the QCD scattering amplitude with vacuum quantum number exchange in the region where the energy is large and the momentum transfer is much smaller than the energy but large compared to the hadronic scale. The appropriate modification of the QCD pomeron partial wave equation is derived. The singularities in the angular momentum which arise at relatively large momentum transfer are studied in double logarithmic approximation. 相似文献
78.
R. Kirschner 《Zeitschrift fur Physik C Particles and Fields》1995,65(3):505-510
We study the pairwise interaction of reggeized gluons and quarks in the Regge limit of perturbative QCD. The interactions are represented as integral kernels in the transverse momentum space and as operators in the impact parameter space. We observe conformal symmetry and holomorphic factorization in all cases. 相似文献
79.
J. Kirschner 《Applied Physics A: Materials Science & Processing》1985,36(3):121-123
Magnetic-structure analysis by means of spin-polarization analysis of the secondary electrons in a scanning electron microscope-type (SEM) experiment is demonstrated, using the LEED spin-polarization detector. The advantages in size, handling ability and efficiency, relevant for SEM operation, are pointed out. Limitations and future development are discussed. 相似文献
80.
I. Kirschner A. C. Bódi R. Laiho E. Lähderanta 《Zeitschrift für Physik B Condensed Matter》1996,101(4):535-537
A new, dynamic procedure is elaborated to create vortex-glass state in high-T c superconductors, which consists of the application of the thermometric mapping method together with a thermal pulse. This results in the direct determination of main parameters of the given state, providing vortex-glass transition temperature of 88 K, correlation length of 2.1 mm, characteristic time of 15 s, moreover static and dynamic scaling exponents of 1.1 and 3.7, respectively. 相似文献